1. Technical Field
The present invention relates to radio detection devices and methods, in particular, to a radio detection device and method with enhanced accuracy.
2. Related Art
Conventionally, a mono-pulse radar is mounted on an own vehicle as a radio detection device (radar) for detecting another vehicle having a possibility of colliding to avoid collision between the own vehicle and the another vehicle (refer to, for example, Japanese Patent Application Laid-Open No. H09-90026, Japanese Patent Application Laid-Open No. H06-150195).
The mono-pulse type is one type of performing angle detection. That is, the mono-pulse radar detects an angle of a detecting object with respect to his/her center direction on the front side. In other words, if the mono-pulse radar is mounted at a front portion of the own vehicle, another vehicle on the front side of the own vehicle becomes the detecting object, and the angle of the another vehicle on the front side of the own vehicle is detected by the mono-pulse radar. If the mono-pulse radar is mounted at a rear portion of the own vehicle, another vehicle on the rear side of the own vehicle becomes the detecting object, and the angle of the another vehicle on the rear side of the own vehicle is detected by the mono-pulse radar.
A brief overview of the mono-pulse type will be further described below with reference to FIGS. 1 and 2.
In the conventional mono-pulse radar, a transmission antenna is arranged, and reception antennas 11L, 11R are respectively arranged at a predetermined spacing in the vicinity of the transmission antenna, as shown in FIG. 1. In the conventional mono-pulse radar, a signal processing unit 12 is also arranged.
A transmission signal from the transmission antenna is reflected by a detecting object, and the reflected signal is received by the reception antennas 11L, 11R as reception signal and provided to the signal processing unit 12. The signal processing unit 12 generates and outputs a difference signal Δ, which is a difference between the two reception signals, and a sum signal Σ, which is a sum of the two reception signals. Each intensity of the difference signal Δ and the sum signal Σ have properties shown in FIG. 2 according to an incoming angle θ, that is, an angle θ with the detecting object.
The mono-pulse radar calculates the angle θ of the detecting object based on a ratio of the signal intensities of the sum signal Σ and the difference signal Δ.